MTBE and BTEX On-site Rapid Screening of Petroleum Contaminated Ground Water

MTBE and BTEX compounds were rapidly screened in petroleum contaminated ground water using solid phase microextraction (SPME) followed by on-site analysis with a GUARDION®-7 portable gas chromatograph-toroidal ion trap mass spectrometer (GC-TMS) from Torion Technologies (USA). The SPME-GC-TMS method can be used to effectively extract, concentrate, separate and detect both MTBE and BTEX quickly and reliably on-site for rapid decision making and cost savings.

The CUSTODION® SPME syringe, together with the GUARDION®-7 gas chromatograph-toroidal ion trap mass spectrometer (GC-TMS) can be used for rapid on-site sample extraction and analysis for sample screening and decision making. Following on-site sample analysis, informed decisions can be made regarding which samples should be sent to a laboratory for confirmatory analysis. In addition, on-site sample collection and extraction using SPME minimizes target analyte losses compared to traditional techniques that risk analyte loss during storage and transport.

The CUSTODION SPME sampling syringe consists of a 1cm fiber coated with a liquid polymer film, solid sorbent or a combination. The SPME fiber is housed in a durable syringe that can be operated with a single hand. Much like a retractable ball point pen, the push button trigger on top of the CUSTODION syringe allows the SPME fiber to be extended and retracted into and out of a protective metal sheath. The SPME fiber traps target analytes from air, headspace (solids or liquids), or direct sampling of liquids and dissolved solid samples.

The CUSTODION PDMS/DVB/CAR SPME syringe used for this application consists of a 1cm length of silica fiber coated with a combination of a liquid polymer film with polydimethylsiloxane (PDMS) and divinylbenzene (DVB) and carboxen (CAR) solid sorbent. Both MTBE and BTEX compounds were extracted directly from petroleum-contaminated water samples.

The attached figure shows the GC-TMS separation of MTBE and BTEX in a ground water sample. All of the compounds were detected and positively identified by the GUARDION-7 compound library. For compounds which co-elute, an on-board deconvolution algorithm was able to positively identify each component based on statistical treatment of the ion fragmentation data.

SPME-GC-TMS is a useful method for on-site sample screening prior to transport for laboratory MTBE and BTEX analysis by GC-TMS. Water or solid samples can be screened using the GUARDION-7 GC-TMS for preliminary information on potential levels of contamination, if any. The CUSTODION SPME syringe and GUARDION-7 GC-TMS provide a fast, easy, accurate and reliable method for sample extraction and on-site analysis.